The present invention is generally related to devices that dissipate heat, and more particularly to heat sinks for electronic and optical devices associated with a high-density architecture.
Electronic and optical network communications devices are often made as small as is practicable because of the overhead costs associated with xe2x80x9crack space.xe2x80x9d Reduction of overall device size may be accomplished in part by increasing the density of components in the device. However, increasing component density results in an increase in the density of energy that must be dissipated from the device as heat. Manufactures of electronic and optical components typically specify a temperature range within which the components can be expected to operate reliably. Techniques for dissipating heat from components have therefore been developed to facilitate component operation in high-density designs. For example, fans may be employed to increase the flow of air across the surface of devices and components. Further, heat sinks that absorb dissipated heat and increase the surface area over which that heat may be dissipated may be employed.
In accordance with the present invention, an apparatus for dissipating heat produced by a device includes a plurality of heat-dissipating regions. Each heat-dissipating region is thermally coupled with at least one component associated with the device. For example, each heat-dissipating region may be coupled with one or more integrated circuit packages. Further, each heat-dissipating region is at least partially thermally isolated from other heat-dissipating regions. All of the heat-dissipating regions associated with the circuit package may be electrically coupled.
Thermal isolation of the heat-dissipating regions advantageously mitigates heat flow between different components associated with the device. Different components associated with the device may generate different amounts of heat. Further, different components associated with the device may have different maximum operating temperatures, i.e., sensitivity to heat. Use of multiple heat-dissipating regions enables individual heat-dissipating regions to be employed with components having particular thermal properties. For example, a heat-dissipating region having greater mass and surface area may be employed with components that are relatively more sensitive to heat or produce relatively greater amounts of heat. Thermal isolation of the heat-dissipating regions associated with the device mitigates heat flow from heat producing components to heat sensitive components.
Electrically coupling the heat-dissipating regions mitigates potential electromagnetic interference from signals generated both inside and outside of the device. The heat-dissipating regions may be formed of an electrically conductive metal that encloses the device on from one to all sides. The electrically conductive metal provides shielding to electromagnetic interference. An electrically conductive and thermally insulative gasket material that couples the heat-dissipating regions further reduces the likelihood of electromagnetic interference by shielding the space between the heat-dissipating regions, and also reduces the likelihood of capacitance buildup between the heat-dissipating regions. The gasket material also allows the heat-dissipating regions to be located in close physical proximity to each other while still providing the benefits noted above.
The present invention is particularly applicable for use with optical transponder devices. Optical transponder devices include a plurality of components such as lasers and silicon based integrated circuits such as multiplexers and demultiplexers. While the performance of both the lasers and the integrated circuits may be adversely affected by high temperatures, the acceptable maximum operating temperature for the lasers is typically lower than that of the integrated circuits. Further, while many electrical and optical circuits generate energy that must be dissipated as heat, the mux/demux integrated circuits associated with the optical transponder may generate an order of magnitude more of such energy in comparison to the lasers. Further, it is desirable to prevent electromagnetic interference from leaking through the transponder enclosure. The present invention mitigates electromagnetic interference and the likelihood of heat generated by the integrated circuits increasing the temperature of the lasers beyond the maximum operating temperature by employing a first heat dissipating region in conjunction with the lasers and a second heat-dissipating region in conjunction with the integrated circuits. In particular, when an air-cooled optical transponder has a plurality of components, including a temperature sensitive component such as an uncooled laser, along with other power generating but less temperature sensitive components such as a laser driver or multiplexer silicon chip, separate heat dissipation elements are employed with the components. One embodiment of the invention is an optical transponder where there is a first heatsink element thermally connected to the laser and pin/tz optical components and a second heatsink used to cool all other power consuming components including any AGC circuits, Clock and data recovery devices, demultiplexers, multiplexers, laser drivers and monitoring and control circuits. These two heatsinks are connected using an electrically conductive but thermally isolating layer so that electromagnetic interference is contained but minimal heat is transferred therebetween. Air is driven to cool the optical transponder from the end where the laser and pin diodes are located.
Certain embodiments of the invention provide a heat dissipating device for use with a circuit package having a plurality of components. The device includes a first thermally conductive portion for thermally coupling with a first component of the circuit package, a second thermally conductive portion for thermally coupling with a second component of the circuit package and an electrically conductive and thermally insulative material. The electrically conductive and thermally insulative material connects to the first and second thermally conductive portions such that the first thermally conductive portion is substantially thermally isolated from the second thermally conductive portion.
Certain embodiments of the invention provide a circuit package having first and second components and first and second thermally conductive portions attached to and thermally coupled with the first and second components respectively. The circuit package also includes an electrically conductive and thermally insulative material coupled with the first and second thermally conductive portion such that the first thermally conductive portion is substantially thermally isolated from the second thermally conductive portion.
Certain embodiments of the invention provide a method for dissipating heat from the circuit package. The method includes dissipating from a first component of the circuit package to a first thermally conductive portion and dissipating from a second component of the circuit package to a second thermally conductive portion and connecting the first thermally conductive portion to the second thermally conductive portion by an electrically conductive and thermally insulative material.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.